Successful management of life-threatening, invasive fungal infections poses difficult challenges to clinicians. Routine therapeutic drug monitoring (TDM) for voriconazole may improve treatment response for patients with a poor response to therapy or toxicity. Voriconazole exhibits nonlinear pharmacokinetics, and significant inter-individual variability in serum concentrations due to polymorphisms in cytochrome P450 and drug-drug interactions. TDM has been considered for pediatric patients and for hematopoietic stem cell transplant recipients. Target trough levels 1 to 5.5 µg/mL have been proposed. The ARK Voriconazole Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of voriconazole in human serum or plasma on automated clinical chemistry analysers. The measurements obtained are used in monitoring levels of voriconazole to ensure appropriate therapy. The ARK Voriconazole Assay is available worldwide outside the U.S.